From 67ce24796584e80cf843b37b09aeb794c9231190 Mon Sep 17 00:00:00 2001
From: "monty@mysql.com" <>
Date: Mon, 6 Dec 2004 02:00:37 +0200
Subject: Add support for up to VARCHAR (size up to 65535) Renamed
 HA_VAR_LENGTH to HA_VAR_LENGTH_PART Renamed in all files FIELD_TYPE_STRING
 and FIELD_TYPE_VAR_STRING to MYSQL_TYPE_STRING and MYSQL_TYPE_VAR_STRING to
 make it easy to catch all possible errors Added support for VARCHAR KEYS to
 heap Removed support for ISAM Now only long VARCHAR columns are changed to
 TEXT on demand (not CHAR) Internal temporary files can now use fixed length
 tables if the used VARCHAR columns are short

---
 myisam/mi_unique.c | 53 ++++++++++++++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 23 deletions(-)

(limited to 'myisam/mi_unique.c')

diff --git a/myisam/mi_unique.c b/myisam/mi_unique.c
index ad685f4cbdc..c03182456df 100644
--- a/myisam/mi_unique.c
+++ b/myisam/mi_unique.c
@@ -93,7 +93,7 @@ ha_checksum mi_unique_hash(MI_UNIQUEDEF *def, const byte *record)
       }
     }
     pos= record+keyseg->start;
-    if (keyseg->flag & HA_VAR_LENGTH)
+    if (keyseg->flag & HA_VAR_LENGTH_PART)
     {
       uint tmp_length=uint2korr(pos);
       pos+=2;					/* Skip VARCHAR length */
@@ -136,7 +136,8 @@ int mi_unique_comp(MI_UNIQUEDEF *def, const byte *a, const byte *b,
   for (keyseg=def->seg ; keyseg < def->end ; keyseg++)
   {
     enum ha_base_keytype type=(enum ha_base_keytype) keyseg->type;
-    uint length=keyseg->length;
+    uint a_length, b_length;
+    a_length= b_length= keyseg->length;
 
     /* If part is NULL it's regarded as different */
     if (keyseg->null_bit)
@@ -154,43 +155,49 @@ int mi_unique_comp(MI_UNIQUEDEF *def, const byte *a, const byte *b,
     }
     pos_a= a+keyseg->start;
     pos_b= b+keyseg->start;
-    if (keyseg->flag & HA_VAR_LENGTH)
+    if (keyseg->flag & HA_VAR_LENGTH_PART)
     {
-      uint tmp_length=uint2korr(pos_a);
-      if (tmp_length != uint2korr(pos_b))
-	return 1;
-      pos_a+=2;					/* Skip VARCHAR length */
-      pos_b+=2;
-      set_if_smaller(length,tmp_length);
+      a_length= uint2korr(pos_a);
+      b_length= uint2korr(pos_b);
+      pos_a+= 2;				/* Skip VARCHAR length */
+      pos_b+= 2;
+      set_if_smaller(a_length, keyseg->length);
+      set_if_smaller(b_length, keyseg->length);
     }
     else if (keyseg->flag & HA_BLOB_PART)
     {
-      /* Only compare 'length' characters if length<> 0 */
-      uint a_length= _mi_calc_blob_length(keyseg->bit_start,pos_a);
-      uint b_length= _mi_calc_blob_length(keyseg->bit_start,pos_b);
+      /* Only compare 'length' characters if length != 0 */
+      a_length= _mi_calc_blob_length(keyseg->bit_start,pos_a);
+      b_length= _mi_calc_blob_length(keyseg->bit_start,pos_b);
       /* Check that a and b are of equal length */
-      if (length && a_length > length)
-	a_length=length;
-      if (!length || length > b_length)
-	length=b_length;
-      if (length != a_length)
-	return 1;
-      /* Both strings are at least 'length' long */
+      if (keyseg->length)
+      {
+        /*
+          This is used in some cases when we are not interested in comparing
+          the whole length of the blob.
+        */
+        set_if_smaller(a_length, keyseg->length);
+        set_if_smaller(b_length, keyseg->length);
+      }
       memcpy_fixed((byte*) &pos_a,pos_a+keyseg->bit_start,sizeof(char*));
       memcpy_fixed((byte*) &pos_b,pos_b+keyseg->bit_start,sizeof(char*));
     }
     if (type == HA_KEYTYPE_TEXT || type == HA_KEYTYPE_VARTEXT)
     {
-      if (mi_compare_text(keyseg->charset, (uchar *) pos_a, length,
-                                           (uchar *) pos_b, length, 0, 0))
-	  return 1;
+      if (mi_compare_text(keyseg->charset, (uchar *) pos_a, a_length,
+                                           (uchar *) pos_b, b_length, 0, 1))
+        return 1;
     }
     else
     {
-      end= pos_a+length;
+      if (a_length != b_length)
+        return 1;
+      end= pos_a+a_length;
       while (pos_a != end)
+      {
 	if (*pos_a++ != *pos_b++)
 	  return 1;
+      }
     }
   }
   return 0;
-- 
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